Merge branch 'patch-9' into 'master'

Added the Revision Control definition

Added the **Revision Control** definition

See merge request !40

source/glossary/index.html.md

@@ -383,6 +383,10 @@ Storage location of all files which are tracked by git.
 *** Needs definition here
+### Revision Control
+
+Also known as version control or source control, is the management of changes to documents, computer programs, large web sites, and other collections of information. Changes are usually identified by a number or letter code, termed the "revision number", "revision level", or simply "revision".
+
 ### RocketChat
 An open source chat application for teams. Very similar to Slack only that is is open-source.